Nature of the beast? Resolving drivers of prey choice, competition and resilience in wolves

狼是欧洲更新世(冰河时代)食肉动物群落中久负盛名的成员，但今天，由于人类迫害和环境变化，这些富有魅力的动物中许多幸存的种群濒临灭绝。作为Keystone捕食者，狼在维持生物多样性方面发挥着至关重要的作用，特别是在控制哺乳动物草食动物和中型食肉动物的数量方面，从而分别限制对植被的过度捕食和对小型脊椎动物的过度捕食。在这方面，它们是古北区北部最有影响力的大型捕食者。因此，它们的活动产生的涟漪可以在整个生态系统中以各种积极的方式感受到，但对于欧洲狼群在不同环境和气候变化情景下的生存能力存在严重关切。因此，一个关键的目标是了解狼是如何适应不断变化的环境的，以便能够适当地调整当前和未来的保护政策。解决这个问题的最佳方法之一是通过研究饮食，因为这与气候和环境(决定哪些猎物种类可用)以及与其他食肉动物对资源的竞争密切相关。我们之前对英国狼化石记录的研究显示，在过去的50万年里，狼的颌骨和牙齿的大小和形状发生了显著变化，结合牙齿断裂和磨损的证据，表明狼改变了它们的饮食(与非肉类食物相比，消耗更多/更少的肉类)以应对环境参数的变化。这种形态变化不容易在现代生态学研究的短时间尺度(几年到几十年)下测量，但丰富的更新世化石记录提供了一系列按年代分辨的狼标本，时间跨度从数万年到数十万年，使得变化模式能够针对各种变量进行充分测试，如气候、环境、食肉动物竞争和猎物可获得性。在NERC资助的两项关于三个不同气候时期(冰期和间冰期)的狼化石遗骸的研究中，我们成功地验证了这些古饮食假设，通过碳和氮稳定同位素分析直接测量骨化学，以验证随着时间的推移不断变化的猎物选择。我们现在建议扩展这项研究，这将是对现代和最近(25万年)欧洲狼化石的饮食最全面和最先进的检查，使用一系列在不同时间尺度上操作的独立代理人。与保护生物学家合作，一个关键目标是整合来自瑞典、波兰和克罗地亚的现代狼的形态和饮食证据，使用无线电项圈狼的GPS数据组合来识别杀戮地点，分析狼的鳞片内容，以及最近扑杀或死亡标本的稳定同位素证据。除了揭示狼饮食的季节和地理变化外，我们的研究还将首次允许：(1)直接比较现代、全新世和更新世狼的饮食；(2)调查饮食的直接(稳定同位素、牙齿微磨损)和间接(形态计量学)测量与来自粪便分析和捕杀地点的实时饮食证据的一致程度；(3)评估饮食对现代狼的形态的影响；(4)通过评估是否复制从现代狼饮食分析中获得的证据，来“实地了解”当前古代饮食方法产生的证据。通过了解过去和现在狼种群的生态轨迹，我们将产生一个新的、基于证据的观点，即气候、猎物选择和环境对欧洲大型食肉动物的影响。除了学术受益者，我们还将通过在Wildwood Trust和艺术委员会的公共宣传接触到新的受众，用于画廊和在线展示。

Wolves were well-established members of the Pleistocene (Ice Age) carnivore community in Europe but today, many surviving populations of these charismatic animals are endangered because of human persecution and environmental change. As keystone predators, wolves play a vital role in maintaining biodiversity, particularly in keeping mammalian herbivore and medium-sized carnivore numbers in check, thereby limiting over-browsing on vegetation and over-predation on small vertebrates respectively. In this regard, they are the most influential large predator in the northern Palaearctic. The ripples from their activity can therefore be felt in diverse positive ways throughout the ecosystem but serious concerns exist as to the viability of European wolf populations under different scenarios of environmental and climate change. A key goal is therefore to understand how wolves have adapted to changing circumstances so that current and future conservation policy can be appropriately tailored.One of the best ways to approach this issue is through the study of diet, since this is closely linked to climate and environment (determining which prey species are available) and to competition for resources from other carnivores. Our previous research into the British fossil wolf record revealed marked changes in the size and shape of the jaws and teeth over the last half a million years, which together with evidence from tooth breakage and wear, indicate that wolves modified their diet (consuming more/less meat versus non-meat foods) in response to changing environmental parameters.Such morphological change cannot readily be measured in the short time scales (years to decades) of modern ecological studies but the rich Pleistocene fossil record offers a chronologically well-resolved series of wolf specimens spanning tens to hundreds of thousands of years, allowing patterns of change to be fully tested against diverse variables such as changing climates, environments, carnivore competition and prey availability. We successfully tested these palaeodietary assumptions in two NERC-funded studies on fossil wolf remains from three different climatic episodes (glacial and interglacial), using direct measurements of bone chemistry through carbon and nitrogen stable isotope analysis in order to verify changing prey choice through time. We now propose to expand this study in what will be the most comprehensive and state-of-the-art examination of diet in modern and recent fossil (<250,000 years) European wolves by using a series of independent proxies operating on different temporal scales. Working with conservation biologists, a key aim is the integration of morphological and dietary evidence from modern wolves from Sweden, Poland and Croatia, using a combination of GPS data on radio-collared wolves to identify kill sites, analysis of the contents of wolf scats, and stable isotope evidence from recently culled or dead specimens. As well as revealing seasonal and geographical variation in wolf diet, our research will allow for the first time: (1) direct comparison of modern, Holocene and Pleistocene wolf diet; (2) investigation of the degree to which direct (stable isotope, dental microwear) and indirect (morphometric) measurements of diet are in step with real-time dietary evidence from scat analyses and kill sites; (3) evaluation of the influence of diet on the morphology of modern wolves and (4) the opportunity to "ground truth" the evidence generated by current palaeodietary approaches, by assessing whether it replicates that obtained from analyses of modern wolf diet. By understanding the ecological trajectory of past and current wolf populations, we will generate a new, evidence-based view of the impacts on European large carnivores of climate, prey choice and environment. As well as academic beneficiaries, we will reach new audiences through public outreach at the Wildwood Trust and art commissions for gallery and online display.